This invention relates to an exothermic metallic composition for a body warmer which comprises at least one of particulate principal metallic components such as iron, aluminum and magnesium; a particulate oxidation agent comprising at least one of ferrosoferric oxide, plumboblumbic oxide, trimanganese tetroxide, black copper oxide and manganese dioxide; water; particulate oxidation assistants in the form of a chloride such as ammonium chloride, calcium chloride or sodium chloride; and active carbon.